A frequency converter for outputting a power to drive a motor, having: an inverter unit for inverting a d.c. power to an a.c. power; a control unit for controlling the inverter unit; and a housing for supporting at least the inverter unit and control unit, wherein a rise time change unit is provided in the housing, the rise time change unit changes a rise time of a waveform of a voltage output from the inverter unit.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of maintenance for a motor driving system having a frequency converter and a motor, wherein an output power from said frequency converter is applied to motor windings of said motor to drive said motor, said method comprising the steps of: obtaining first characteristics and second characteristics, wherein said first characteristics indicate a relation between a rise time of a voltage to be applied to the motor windings and a value of a voltage at which a partial discharge will not occur between motor windings, and said second characteristics indicate a relation between inductances of reactors provided between the frequency converter and motor and a change in said rise time of the voltage; obtaining, based on the first characteristics, a surge voltage suppressing rise time of a voltage output from the frequency converter is obtained at which the partial discharge is suppressed from being generated between motor windings; obtaining, based on the surge voltage suppressing rise time and the second characteristics, an inductance satisfying the surge voltage suppressing rise time; and arranging a reactor having the obtained inductance between the frequency converter and the motor.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
October 31, 2007
March 31, 2009
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